Tanzanite: Vivid Blue Gemstone That’s Red Hot

Anyone who’s seen the exquisite beauty of high quality tanzanite rings immediately falls in love with the bright blue stone. But if your tastes run to vintage and antique jewelry, don’t bother searching for antique tanzanite engagement rings – you won’t find any. The reason for that is simple: even though it is as spectacular as revered precious stones like sapphires, opals, rubies and emeralds, tanzanite was discovered fewer than fifty years ago. The stones can certainly be placed into vintage settings, but tanzanite is the “new kid on the block” which has become exceptionally popular since its discovery.

Just how popular is tanzanite? It’s the second most purchased blue gemstone in the world (trailing only sapphire) and the fifth most popular stone of any color. And many people actually prefer tanzanites over sapphires because their color is more vibrant. Another measure of the impact that tanzanite has made in the marketplace is that it has been added to the gem trading association’s official list of birthstones (as a primary December birthstone), which hadn’t been changed since its creation in 1912. The United States is by far the biggest market for the stone, with nearly 75% of all tanzanite jewelry sold in America.

In addition to its rare beauty, tanzanite is also a rare stone. It is only mined in one nation in the world and the supply is quickly dwindling. Those buying a tanzanite ring are not only purchasing a gorgeous piece, but ensuring that they own a ring which will undoubtedly appreciate in value over the years.

How did this striking gemstone go undiscovered for so long, and then become so popular so quickly? That’s an interesting story – one which we’ll investigate before we look at the process of choosing the perfect tanzanite ring.

Tanzanite and Diamond 14K White Gold 3-Stone Ring / Ice.com

The Discovery of a New Gemstone

It was 1967 in Northern Tanzania when an Indian sapphire prospector was taken to the Merelani Hills near Mount Kilimanjaro by a group of Masai natives. According to legend, they had seen blue stones in the area after lightning caused a large brush fire, which turned what had been ordinary, rough stone a very deep blue. Whether the legend is true or not, the prospector believed he had discovered royal blue sapphire and filed a mining claim. Shortly thereafter, as more and more miners found deposits of the stone and filed their own claim, experts realized that the stone wasn’t sapphire, but a completely unknown gemstone.

The new gem, never seen before, was a variety of the common mineral called zoisite. However, it also contained the chemical element vanadium; that mix, when combined with the geology of the area and millions of years (and apparently, the heat of the brush fire), created the beautiful blue color. Even more importantly, the crystal structure of the stone was trichroic – in other words, it generated a number of different colors from each of the axes inside, creating a unique play of color when hit by light.

The stone was a sensation. Newspapers and magazines throughout Europe and America publicized the discovery of the stone, and Tiffany & Co. hopped on the bandwagon quickly, naming it tanzanite and marketing it prominently. But there was a catch. The supply and production of tanzanite was anything but stable, partly due to the murder of the original prospector who discovered it and partly because of the area’s political climate. For those reasons, Tiffany and others were unable to meet demand for this new and beautiful gemstone and the big tanzanite boom was over almost before it had begun.

A short time later, the Tanzanian government took control of the resource and made several attempts to revive interest in tanzanite, and finally successful in the 1990s. Once there was a reliable supply of this striking blue gem, interest in tanzanite again soared and this time, there was enough of the material to produce and sell tanzanite rings, earrings, necklaces and bracelets to eager customers.

Even today, the only place where tanzanite has been found or mined is in an area that’s four kilometers square in the foothills of Mount Kilimanjaro; even though that land is part of a much larger geological belt, none of the stone has been discovered anywhere else in the formation. As time has passed, experts have concluded that it’s unlikely any new tanzanite mining areas will ever be discovered, and that the world’s supply of the gemstone will dry up sooner rather than later – most likely within 20 to 30 years.

Oval Tanzanite and Diamond Ring in 14K White Gold / Zales.com

More About Tanzanite

A number of gemstones are lustrous. Few have the natural luster of a beautiful tanzanite, because of the internal crystal axes which can show a kaleidoscope of colors including light and dark blues (from royal blue to periwinkle), violets (from indigo to lilac), and at times browns and grays, depending on the viewing angle. High quality tanzanites can vary in color from a rich blue to a stunning violet; the stones are usually either described as “violetish-blue” (vB) or “bluish-violet” (bV) with the former meaning the gemstone is predominantly blue, the latter describing a stone which is primarily violet.

On a per-carat basis, blue stones are usually worth more than their violet counterparts because they’re rarer. It’s extremely difficult for a craftsman to cut a large blue tanzanite into smaller ones since the blue color normally emanates from the shortest axis in the crystal, the toughest to cut properly. The most sought-after blue tanzanites are known as D-block stones, named after the section of the Tanzanian fields where the deepest blue stones are found and from which they are mined.

Tanzanites aren’t graded in exactly the same way that diamonds are, because their characteristics don’t lend themselves to that type of system. Instead, they’re graded similarly to sapphires and other colored stones, with color tone and saturation the primary considerations (along with the gem’s size). Clarity and cut do still matter, but don’t carry as much weight. Generally speaking, the intensity of a tanzanite’s color determines its value, with the most vibrantly-colored gems the rarest stones with very high prices. We’ll discuss this in more detail shortly.

Tanzanite rings (or other jewelry featuring the stone) do require a little more care than their diamond or sapphire counterparts. Diamond ranks at 10 on the Mohs scale of mineral hardness and sapphire is just slightly softer at 9. Tanzanite, however, ranks between 6.5 and 7, meaning it’s a softer stone and more prone to cracks or breaks. It’s still relatively hard (steel, for example, comes in between 4 and 5 on the Mohs scale) and won’t be damaged during everyday wear, but it’s best to take off your tanzanite ring if you’re doing the dishes or fixing the car. Gorgeous tanzanite engagement rings are best worn when they can safely be shown off.

Tanzanite 14K White Gold Cocktail Ring with Diamond Accents / Ice.com

Evaluating Tanzanite

As we’ve mentioned, the color of a tanzanite (along with its size) largely determines its value and price. Here’s how the leading independent gemological laboratory, GIA (Gemological Institute of America), evaluates tanzanite.

Hue: The gem will either be graded as vB or bV; you may remember that those stand for violetish-blue (with blue dominant) or bluish-violet (with violet dominant). A vB tanzanite is more valuable.

Tone: This describes the darkness of the stone’s color. The tone scale runs from zero (colorless) to ten (black), but all tanzanites will rank between two (very light) and eight (very dark). The higher, the better.

Saturation: This is a scale running from one to six, on which a stone’s color intensity or purity is judged. Tanzanites which are graded between one and three on the saturation scale will have brown or gray tones evident in their color. The best stones are rated four (moderately strong), five (strong) or six (vivid) – as you’ve probably guessed, the higher the rating, the better and more valuable the tanzanite.

Overall grade: GIA sums up its grading by combining all of the scores in one ranking. An exceptional stone would, for example, be graded vB 7/6, which means the tanzanite is violetish-blue with dark tone and vivid saturation.

There are also, of course, GIA ratings for a tanzanite’s clarity and cut. They’re a little different than you’re probably familiar with, though, because they’re not exactly the same as a diamond’s grades.

For clarity, detailed descriptors don’t carry the same weight that they do for diamonds. Tanzanite will be graded as eye-clean, slightly included, moderately included, heavily included or severely included; since tanzanite is usually a clean stone, you’re not setting your sights too high by insisting on a gem that’s eye-clean.

Rating tanzanite cuts is difficult, because each stone must be cut differently in order to bring out its color and brilliance. For that reason, GIA rates cut on a scale from excellent to poor primarily by judging things like symmetry and well-cut facets. However, the cut’s “score” means less than the tanzanite’s actual light performance and how it looks to your eye – if the stone looks like it’s glowing outward, that’s good, if it appears black or transparent, that’s bad. A few things that the untrained eye can see when inspecting a tanzanite ring: the gemstone should look symmetrical, the facets should come together at points and not circles, and the pavilion should be round, pointed and not too deep. Although there’s no “perfect” shape for a tanzanite, the most commonly seen are oval, trilliant, pear shaped and cushion cut.

Finally, we come to the question of carats. Since carat is a measurement of weight, it’s still the standard that’s used to indicate the “size” of a tanzanite. Diamonds are much heavier than tanzanites, though, and they’re cut very differently – so you can’t put one carat diamonds and one carat tanzanites next to each other and expect them to look anything alike. Most tanzanites sold at retail are between one and ten carats in weight so it’s unusual to see stones smaller than one carat in tanzanite engagement rings, and it’s common to see higher quality tanzanite rings offered at three to five carats. The good news is that the per carat retail price of high quality tanzanite is in the range of $2000 for larger stones, well below that of a sapphire or diamond. The price is expected to increase over time, as the supply of tanzanite grows lower.

Tanzanite Ring Diamond Accents Sterling Silver / Kay.com

Other Considerations

Here are a few more things to be aware of when shopping for a tanzanite ring.

You may not be able to immediately tell whether a stone is vB or bV, because sunlight or other white light makes the stone look bluer than it might be, and indoor lighting can make a tanzanite look more violet than it really is.

There are many tanzanite rings on the market which feature small stones with pastel colors ranging from lilac to soft blue-gray. The reason is simple: most of the tanzanite mined and sold is pastel-colored. To some people, the stones are still pretty – and there’s nothing wrong with that, particularly since these rings will be much less expensive than ones with deep blue stones and great color play.

A related question you may be asking: why are most small tanzanites pastels? It’s because the small stones don’t do a good job of holding deep color; most truly outstanding tanzanites are over two or three carats in size. A stone that’s half-a-carat or one carat shouldn’t be expected to be better than a medium blue, and you’d be extremely fortunate to find one rated as a 6/5 or 6/6 on the GIA scale.

You may find jewelers or online sites offering tanzanite rings with all sorts of confusing descriptions or letter-based grading scales (like “investment grade” or “AAA”). Be aware that those labels are strictly subjective and often assigned by the jeweler himself.

Almost all tanzanites are heat treated to bring out their vibrant blue color and that treatment does not damage the stone in any way, so there’s no reason to worry about a heat-treated stone. However, if you see a perfectly clear stone with absolutely no light play, it may be synthetic. Some unscrupulous vendors also apply cobalt to pale tanzanites to make them appear bluer than they really are, so be careful who you buy from.

Tanzanite rings are so popular because they’re so beautiful. The vivid blue and violet colors exhibited by a quality tanzanite ring are unmatched even by the beloved sapphire. The fact that this stone will become extremely rare in the coming decades, as existing deposits of tanzanite are depleted, makes it a smart investment as well.